Abstract

Narrowband imaging is a highly successful approach for finding large numbers of high-redshift Ly α emitting galaxies (LAEs) up to z ∼ 6.6. However, at z ≳ 7 there are as of yet only three narrowband selected LAEs with spectroscopic confirmations (two at z ∼ 6.9–7.0, one at z ∼ 7.3), which hinders extensive studies on cosmic reionization and galaxy evolution at this key epoch. We have selected 23 candidate z ∼ 6.9 LAEs in COSMOS field with the large area narrowband survey Lyman-Alpha Galaxies at the End of Reionization (LAGER). In this work, we present spectroscopic follow-up observations of 12 candidates using the Inamori Magellan Areal Camera and Spectrograph on Magellan. For nine of these, the observations are sufficiently deep to detect the expected lines. Ly α emission lines are identified in six sources (yielding a success rate of 2/3), including three luminous LAEs with Ly α luminosities of L {sub Lyα} ∼ 10{sup 43.5} erg s{sup −1}, the highest among known spectroscopically confirmed galaxies at ≳7.0. This triples the sample size of spectroscopically confirmed narrowband selected LAEs at z ≳ 7, and confirms the bright-end bump in the Ly α luminosity function we previously derived based on themore » photometric sample, supporting a patchy reionization scenario. Two luminous LAEs appear physically linked with a projected distance of 1.1 pMpc and velocity difference of ∼170 km s{sup −1}. They likely sit in a common ionized bubble produced by themselves or with close neighbors, which reduces the intergalactic medium attenuation of Ly α . A tentative narrow N v λ 1240 line is seen in one source, hinting at activity of a central massive black hole with metal-rich line-emitting gas.« less

@article{osti_22654398,
title = {First Spectroscopic Confirmations of z ∼ 7.0 Ly α Emitting Galaxies in the LAGER Survey},
author = {Hu, Weida and Wang, Junxian and Kang, Wenyong and Kong, Xu and Yang, Huan and Zheng, Zhen-Ya and Jiang, Chunyan and Malhotra, Sangeeta and Rhoads, James and Gonzalez, Alicia and Tilvi, Vithal and Infante, Leopoldo and Walker, Alistair R. and Jiang, Linhua and Hibon, Pascale and Barrientos, L. Felipe and Galaz, Gaspar and Finkelstein, Steven and Zheng, XianZhong, E-mail: urverda@mail.ustc.edu.cn, E-mail: jxw@ustc.edu.cn, E-mail: zhengzy@shao.ac.cn, E-mail: Sangeeta.Malhotra@asu.edu, E-mail: James.Rhoads@asu.edu, E-mail: linfante@carnegiescience.edu},
abstractNote = {Narrowband imaging is a highly successful approach for finding large numbers of high-redshift Ly α emitting galaxies (LAEs) up to z ∼ 6.6. However, at z ≳ 7 there are as of yet only three narrowband selected LAEs with spectroscopic confirmations (two at z ∼ 6.9–7.0, one at z ∼ 7.3), which hinders extensive studies on cosmic reionization and galaxy evolution at this key epoch. We have selected 23 candidate z ∼ 6.9 LAEs in COSMOS field with the large area narrowband survey Lyman-Alpha Galaxies at the End of Reionization (LAGER). In this work, we present spectroscopic follow-up observations of 12 candidates using the Inamori Magellan Areal Camera and Spectrograph on Magellan. For nine of these, the observations are sufficiently deep to detect the expected lines. Ly α emission lines are identified in six sources (yielding a success rate of 2/3), including three luminous LAEs with Ly α luminosities of L {sub Lyα} ∼ 10{sup 43.5} erg s{sup −1}, the highest among known spectroscopically confirmed galaxies at ≳7.0. This triples the sample size of spectroscopically confirmed narrowband selected LAEs at z ≳ 7, and confirms the bright-end bump in the Ly α luminosity function we previously derived based on the photometric sample, supporting a patchy reionization scenario. Two luminous LAEs appear physically linked with a projected distance of 1.1 pMpc and velocity difference of ∼170 km s{sup −1}. They likely sit in a common ionized bubble produced by themselves or with close neighbors, which reduces the intergalactic medium attenuation of Ly α . A tentative narrow N v λ 1240 line is seen in one source, hinting at activity of a central massive black hole with metal-rich line-emitting gas.},
doi = {10.3847/2041-8213/AA8401},
journal = {Astrophysical Journal Letters},
number = 2,
volume = 845,
place = {United States},
year = 2017,
month = 8
}

We present the first results from the ongoing Lyman Alpha Galaxies in the Epoch of Reionization (LAGER) project, which is the largest narrowband survey for z ∼ 7 galaxies to date. Using a specially built narrowband filter NB964 for the superb large-area Dark Energy Camera (DECam) on the NOAO/CTIO 4 m Blanco telescope, LAGER has collected 34 hr NB964 narrowband imaging data in the 3 deg{sup 2} COSMOS field. We have identified 23 Ly α Emitter candidates at z = 6.9 in the central 2-deg{sup 2} region, where DECam and public COSMOS multi-band images exist. The resulting luminosity function (LF)more » can be described as a Schechter function modified by a significant excess at the bright end (four galaxies with L {sub Lyα∼} 10{sup 43.4±0.2} erg s{sup −1}). The number density at L {sub Ly} {sub α} ∼ 10{sup 43.4±0.2} erg s{sup −1} is little changed from z = 6.6, while at fainter L {sub Lyα} it is substantially reduced. Overall, we see a fourfold reduction in Ly α luminosity density from z = 5.7 to z = 6.9. Combined with a more modest evolution of the continuum UV luminosity density, this suggests a factor of ∼3 suppression of Ly α by radiative transfer through the z ∼ 7 intergalactic medium (IGM). It indicates an IGM neutral fraction of x {sub Hi} ∼ 0.4–0.6 (assuming Ly α velocity offsets of 100–200 km s{sup −1}). The changing shape of the Ly α LF between z ≲ 6.6 and z = 6.9 supports the hypothesis of ionized bubbles in a patchy reionization at z ∼ 7.« less

The fourth generation of the Sloan Digital Sky Survey (SDSS-IV) began observations in 2014 July. It pursues three core programs: the Apache Point Observatory Galactic Evolution Experiment 2 (APOGEE-2), Mapping Nearby Galaxies at APO (MaNGA), and the Extended Baryon Oscillation Spectroscopic Survey (eBOSS). As well as its core program, eBOSS contains two major subprograms: the Time Domain Spectroscopic Survey (TDSS) and the SPectroscopic IDentification of ERosita Sources (SPIDERS). This paper describes the first data release from SDSS-IV, Data Release 13 (DR13). DR13 makes publicly available the first 1390 spatially resolved integral field unit observations of nearby galaxies from MaNGA. Itmore » includes new observations from eBOSS, completing the Sloan Extended QUasar, Emission-line galaxy, Luminous red galaxy Survey (SEQUELS), which also targeted variability-selected objects and X-ray-selected objects. DR13 includes new reductions of the SDSS-III BOSS data, improving the spectrophotometric calibration and redshift classification, and new reductions of the SDSS-III APOGEE-1 data, improving stellar parameters for dwarf stars and cooler stars. DR13 provides more robust and precise photometric calibrations. Value-added target catalogs relevant for eBOSS, TDSS, and SPIDERS and an updated red-clump catalog for APOGEE are also available. This paper describes the location and format of the data and provides references to important technical papers. The SDSS web site, http://www.sdss.org, provides links to the data, tutorials, examples of data access, and extensive documentation of the reduction and analysis procedures. DR13 is the first of a scheduled set that will contain new data and analyses from the planned ~6 yr operations of SDSS-IV.« less

The fourth generation of the Sloan Digital Sky Survey (SDSS-IV) began observations in 2014 July. It pursues three core programs: the Apache Point Observatory Galactic Evolution Experiment 2 (APOGEE-2), Mapping Nearby Galaxies at APO (MaNGA), and the Extended Baryon Oscillation Spectroscopic Survey (eBOSS). As well as its core program, eBOSS contains two major subprograms: the Time Domain Spectroscopic Survey (TDSS) and the SPectroscopic IDentification of ERosita Sources (SPIDERS). This paper describes the first data release from SDSS-IV, Data Release 13 (DR13). DR13 makes publicly available the first 1390 spatially resolved integral field unit observations of nearby galaxies from MaNGA. Itmore » includes new observations from eBOSS, completing the Sloan Extended QUasar, Emission-line galaxy, Luminous red galaxy Survey (SEQUELS), which also targeted variability-selected objects and X-ray-selected objects. DR13 includes new reductions of the SDSS-III BOSS data, improving the spectrophotometric calibration and redshift classification, and new reductions of the SDSS-III APOGEE-1 data, improving stellar parameters for dwarf stars and cooler stars. DR13 provides more robust and precise photometric calibrations. Value-added target catalogs relevant for eBOSS, TDSS, and SPIDERS and an updated red-clump catalog for APOGEE are also available. This paper describes the location and format of the data and provides references to important technical papers. The SDSS web site, http://www.sdss.org, provides links to the data, tutorials, examples of data access, and extensive documentation of the reduction and analysis procedures. DR13 is the first of a scheduled set that will contain new data and analyses from the planned ~6 yr operations of SDSS-IV.« less

The Sloan Digital Sky Survey III (SDSS-III) presents the first spectroscopic data from the Baryon Oscillation Spectroscopic Survey (BOSS). This ninth data release (DR9) of the SDSS project includes 535,995 new galaxy spectra (median z {approx} 0.52), 102,100 new quasar spectra (median z {approx} 2.32), and 90,897 new stellar spectra, along with the data presented in previous data releases. These spectra were obtained with the new BOSS spectrograph and were taken between 2009 December and 2011 July. In addition, the stellar parameters pipeline, which determines radial velocities, surface temperatures, surface gravities, and metallicities of stars, has been updated and refinedmore » with improvements in temperature estimates for stars with T{sub eff} < 5000 K and in metallicity estimates for stars with [Fe/H] > -0.5. DR9 includes new stellar parameters for all stars presented in DR8, including stars from SDSS-I and II, as well as those observed as part of the SEGUE-2. The astrometry error introduced in the DR8 imaging catalogs has been corrected in the DR9 data products. The next data release for SDSS-III will be in Summer 2013, which will present the first data from the APOGEE along with another year of data from BOSS, followed by the final SDSS-III data release in 2014 December.« less